It has been know that polymers having a tricyclo[5.2.1.0.sup.2,6 ]decanyl acrylate or methacrylate as a monomeric component are useful as painting materials and optical materials (as described, for instance in Japanese Patent Application (OPI) Nos. 168009/84, 124605/85, 156708/85 and 166351/85) (the term "OPI" as used herein means an unexamined published Japanese patent application). However, such polymers are defective in that their resistance to water and fouling is insufficient to provide satisfactory paint coatings and that they are too hygroscopic to provide optical materials.
In order to reduce the hygroscopicity of these materials, it is proposed to introduce one or more bromine atoms into the decanyl group (as described in Japanese Patent Application (OPI) No. 124605/85). However, such materials are still insufficient in hygroscopicity. Moreover, the materials have a high refractive index.